Fixing 2D canvas invalidation region tracking.

Source/platform/graphics/ImageBuffer.cpp

 /*
  * Copyright (c) 2008, Google Inc. All rights reserved.
  * Copyright (C) 2009 Dirk Schulze <krit@webkit.org>
  * Copyright (C) 2010 Torch Mobile (Beijing) Co. Ltd. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
@@ skipping 105 matching lines @@
 {
     return m_surface->isValid() || m_surface->restore();
 }
 
 void ImageBuffer::notifySurfaceInvalid()
 {
     if (m_client)
         m_client->notifySurfaceInvalid();
 }
 
+void ImageBuffer::didPresent()

[Stephen White, 2014/07/17 15:28:19]

It seems unfortunate that ImageBuffer has all this functionality that's not
really related to being a leaf class bag o' pixels. But I guess that ship has
sailed.

+{
+    if (m_client)
+        m_client->didPresent();
+}
+
 static SkBitmap deepSkBitmapCopy(const SkBitmap& bitmap)
 {
     SkBitmap tmp;
     if (!bitmap.deepCopyTo(&tmp))
         bitmap.copyTo(&tmp, bitmap.colorType());
 
     return tmp;
 }
 
 PassRefPtr<Image> ImageBuffer::copyImage(BackingStoreCopy copyBehavior, ScaleBehavior) const
@@ skipping 273 matching lines @@
     if (!encodeImage(imageData, mimeType, quality, &encodedImage))
         return "data:,";
 
     Vector<char> base64Data;
     base64Encode(encodedImage, base64Data);
 
     return "data:" + mimeType + ";base64," + base64Data;
 }
 
 } // namespace WebCore